I have the same one and I'm assuming that it's a 1.6b. I know I have to open it to be 100% sure but I'm not too eager to do that just yet since it's so new....but it's days of being a stock box are numbered.

Look, there's plenty of theories on how to tell without opening the xbox based on manufacture date or serial number. None work all the time. The only way to be 100% sure of what you have is to open then xbox. If you're going to mod it what; the big deal anyhow? As far as why none of this stuff holds, true it's all in MSs court and there are plenty of ideas why, but nothing proven. So just open the Xbox to find out your version.

The hardest part about opening it was having to rip the two stickers that covered the two middle screws. It was dead easy to get to the main board. The LPC was a little smaller than I expected but I think that installing a chip will be pretty easy. Now it's just finding an easy to use & cheap chip to install.